State-of-the-art wireless communication networks provide the capability of handling voice communications as well as multimedia transmissions such as the transmission of photos, videos, music, and the like. Various protocols for incorporating multimedia into a wireless communication networks are specified by the 3rd Generation Partnership Project (3GPP), which is a joint standardization project of the various standardization bodies of Europe, Japan, Korea, USA and China. 3GPP protocols may be exploited, for example, within second generation wireless communication networks such as those configured in accordance with Global Network for Mobile Communications (GSM) standard, as well as in third generation networks such as those configured in accordance with the Universal Mobile Telecommunications Network (UMTS) standard.
Within early 3GPP protocols, such as 3G.324 of 3GPP R-99, only “pure” multimedia or pure speech calls could be set up. Users wishing to temporarily switch between speech and multimedia would thereby need to hang up and redial to switch modes. To address this problem, a new functionality (referred to as Service Change and Unrestricted Digital Interface (UDI) Fallback (SCUDIF) functionality) has been incorporated within more recent 3GPP protocols, such as 3GPP Rel-5. SCUDIF provides capability to fallback to a single service, i.e. either speech or multimedia, at call set up, as well as to switch services during the active phase of the call.
The fallback functionality allows calls being set-up as multimedia calls to fallback to speech calls if the network or terminating user equipment (e.g., the handset of the user receiving the call) does not accommodate multimedia. By providing a fallback functionality, fewer failed calls occur.
The mode switch functionality allows users to switch from multimedia to speech or from speech to multimedia during the active phase of the call. To this end, the user wishing to trigger a mode switch enters appropriate commands into his or her terminal for enabling the switch. These commands are forwarded through intermediate wireless communication networks, such as Mobile Services Switching Centers (MSCs), to the handset terminal of the other user of the call. If the mode switch is from multimedia to speech, the switch is automatically enabled without requiring any response by the remote user.
However, mostly for privacy reasons, if the switch is from a speech to multimedia, the protocol specifies that the remote user (i.e., the user receiving the request) must be permitted to first confirm the switch. That is, the remote user has the opportunity to refuse any request to switch from speech to multimedia. This prevents, for example, the receiving party of a wireless telephone call to suddenly receive unwanted images or music during what was expected to have been a pure speech call. Accordingly, the remote user is prompted to accept or decline the requested mode switch.
Within wireless communications networks employing an In-Call Modification (ICM) procedure, a timer is activated whenever a user terminal is prompted to respond to a modification to an on-going call and, if no response is received before the timer expires, the call is automatically dropped. This procedure is primarily provided to prevent calls from remaining connected indefinitely, if the terminal of the remote user is not capable of responding to the requested in-call modification. Typically, the timer (referred to herein as a “call drop timer”) is typically set to thirty seconds.
Problems, however, arise when implementing SCUDIF within a network employing a call drop timer, such as ICM networks. As noted, with SCUDIF the user receiving a request for a switch between speech and multimedia is prompted to confirm the mode switch. If the user fails to respond within the thirty second period provided by the call drop timer, the call is automatically dropped by ICM (or manually disconnected before the thirty second period by the user that requested the mode switch). Circumstances may arise wherein the receiving user does not realize that he or she is obligated to respond to the mode switch request or is perhaps incapable of responding promptly for one reason or another. For example, the user may simply be taking another call via call waiting while the call subject to the mode switch request is on hold. Moreover, depending upon the implementation, the receiving user may not even be notified that a timer limit has been set and hence may simply not be aware that a deadline has been imposed. In any case, the call will be automatically disconnected after timer expiry by ICM if no response is entered, to the likely frustration of both parties to the telephone call.
Therefore, it would be highly desirable to provide wireless communications components, such as user terminals or MSCs, and methods of operating same with the capability to prevent such automatic call drops, and it is to that end that the invention is primarily directed.